As broadcasting have evolved from analog to digital, a digital broadcasting emitting system has been required to transmit system information (SI) and program guide (PG) of broadcasting programs to viewers through a broadcasting channel in order to allow the viewers to conveniently search and select a desire broadcasting program.
The advanced television system committee (ATSC) defines a program and system information protocol (PSIP) to transmit the system information (SI) and the program guide (PG) as a transport stream (TS) based on a MPEG-2 system standard.
FIG. 1 is a block diagram illustrating a system defined by a program metadata communication protocol PMCP. The ATSC designates a broadcasting emitting system that transmits the SI and PG of broadcasting programs through a transport stream based on the PSIP as a PSIP server or a PSIP generator. PSIP information is firstly composed by a program director through a program management system, and the composed PSIP information is transmitted to a PSIP server. The composed PSIP information may be updated, added or deleted if a broadcasting schedule changes before finally transmitting corresponding broadcasting programs.
The broadcasting schedule changes in a broadcasting transmission controlling device such as a traffic system, an automation system, and a MPEG controller. Accordingly, the broadcasting transmission controlling device must have a capability of notifying the changes of the broadcasting schedule to the PSIP server so the PSIP server updates the PSIP information with the changed program guide.
Since interfaces for exchanging program guide with modified information were independently defined by operators, interoperability among digital broadcasting emitting systems developed by many companies, that is, interoperability between a broadcasting transmission controlling device and the PSIP server, cannot be secured. This causes the increase of effort and cost to embody an interface between broadcasting devices when a broadcasting emitting system is built in a view of an operator or a developer of a digital broadcasting emitting system.
In order to overcome the problem described above, the ATSC defines ATSC A/76 standard, the PMCP. The PMCP introduces a metadata structure for exchanging standard PSIP information among devices constituting a digital broadcasting emitting system and a emitting method.
FIG. 2 is a metadata structure defined in a PMCP. As shown in FIG. 2, the structure of the PMCP metadata 200 includes a message state metadata 210, a transport stream metadata 220, a channel metadata 230, a show metadata 240, a PSIP event metadata 250, a time metadata 260, a rating metadata 270 and a private PMCP information metadata 280. The message state metadata 210 describes the validity of a transmitted message and a processing state. The transport stream metadata 220 describes the information of transport stream. The channel metadata 230 describes a virtual channel and channel tuning information. The show metadata 240 describes a play list of shows used to a program guide. The PSIP event metadata 250 describes a program guide. The time metadata 260 describes system time information. The rating metadata 270 describes ratings of broadcasting programs. The private PMCP information metadata 280 describes system level information defined by a PMCP user.
The PMCP metadata 200 describes information for the PSIP server to generate a transport stream for transmitting PSIP/PSI, where PSI stands for program specific information. That is, the PMCP was designed to provide a metadata for a broadcasting emitting system to transmit PSIP/PSI which is system information and program guide only for audio/video broadcasting programs in a digital broadcasting environment. The audio/video broadcasting program refers a broadcasting program that is composed of audio only, video only, or audio and video.
The conventional digital broadcasting environment simply provides audio/video broadcasting programs to viewers. Such a conventional digital broadcasting environment has evolved to a digital data broadcasting environment that provides not only audio/video broadcasting programs but also various related services to views by transmitting data with the audio/video broadcasting programs.
In order to provide a data broadcasting service, it requires a conventional digital broadcasting emitting system to have a data broadcasting transmission device for encoding data broadcasting contents according to a data broadcasting protocol and outputting the encoded data broadcasting contents as a MPEG-2 transport stream. The data broadcasting transmission device is designated as a data server 160 or a data stream generator in general.
The data server must receive program guide and encoding information for generating data stream as like the PSIP server for a digital service. The broadcasting transmission controlling device such as a traffic system, an automation system, and a MPEG control system must have capability of modifying program guide and encoding information.
Since the conventional PMCP does not describe the program guide and encoding information for data broadcasting, the conventional PMCP is not suitable as an interface of a data broadcasting emitting system to secure the interoperability for data broadcasting transmission. Therefore, there is a demand for a system and method for securing the interoperability between the data server, which is newly added for data broadcasting, and other broadcasting devices for transmitting data broadcasting programs.